Isotopic effects on vibrational modes of thermal double donors in Si and Ge

The local vibrational modes of thermal double donors in Si and Ge are investigated by FTIR and ab initio modelling. At most, two oxygen modes are detected from each donor, which exhibit regular shifts with increasing donor number. By using mixtures of 16 O and 18 O , it is found that in Si the upper...

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Bibliographic Details
Published in:Physica. B, Condensed matter Condensed matter, 2001-12, Vol.308, p.290-293
Main Authors: Murin, L.I., Lindström, J.L., Markevich, V.P., Hallberg, T., Litvinov, V.V., Coutinho, J., Jones, R., Briddon, P.R., Öberg, S.
Format: Article
Language:English
Subjects:
Germanium
NATURAL SCIENCES
NATURVETENSKAP
Oxygen
Scientific Computing
Silicon
Teknisk-vetenskapliga beräkningar
Thermal donors
Vibrational modes
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Summary:The local vibrational modes of thermal double donors in Si and Ge are investigated by FTIR and ab initio modelling. At most, two oxygen modes are detected from each donor, which exhibit regular shifts with increasing donor number. By using mixtures of 16 O and 18 O , it is found that in Si the upper band does not yield any new modes suggesting that any oxygen atom is decoupled from any other. However, the lower frequency bands exhibit unique mixed modes proving for the first time that oxygen atoms are coupled together and in close spatial proximity. Ab initio calculations demonstrate that the modes and their isotopic shifts are consistent with a model involving two parallel chains of oxygen atoms linking second neighbour Si atoms, terminated by O-atoms close to the normal position for interstitial O.
ISSN:0921-4526
1873-2135
1873-2135
DOI:10.1016/S0921-4526(01)00700-1